Various toys having not only a fixed shape but also capable of wobbling have been known. Most of the prior art wobbling toys are moved by mechanically articulated manipulation, and in order to make the toys dance to the accompaniment of music, complexity of mechanism involving a motor or gears is needed for moving articulations inside the doll. Research and development have advanced in moving legged multi-articulate bipedal mobile robots called ‘humanoid robots’ which mimic the human body mechanism and the motion of the human beings and are capable of walking, walking up stairs and performing dancing motions.
However, the legged mobile robots suffer from shortcomings in that the robots are prone to tumble failing to express excessive motions, and can express only simple foot steps with mostly arm movement. Numerous innovations for the legged robots have been provided in the prior art that will be described.
For example, U.S. Pat. Nos. 6,802,382, 7,053,577 and 7,061,200 teach a bipedal walking robot equipped with various sensors and actuators. The robots disclosed in these patents have a limit of mimicking only the motions of human beings. Moreover, the currently commercialized humanoid robots are very expensive, together with difficulties of using the humanoid robots as a concept of toy that dances. As a result, a mobile doll disposed inside liquid as an ornament or a toy capable of expressing a flexible and subtle motion has been disclosed.
Another example, U.S. Pat. No. 5,435,086 teaches an apparatus rotating a doll disposed in a liquid-contained vessel using a magnet, and other examples, U.S. Pat. Nos. 4,578,044, 5,272,681, 6,675,513 and 6,814,646 propose an apparatus operating in liquid a buoyed doll hung in a string by using magnetic force.
Still further examples, U.S. Pat. Nos. 5,301,444, 5,685,096 and 6,665,964 suggest one form of self-propelled fish-like aquatic toy capable of being freely driven through the water by outside magnetic force applied to a permanent magnet inserted therein.
These prior art toys or dolls thus explained suffer from shortcomings in that motions are very slow or toys are hung in a string to only perform a simple repeated motion, such that high complex and difficult movements including brake dances involving free stepping or rotations cannot be expressed.